1. Field of the Invention
The present invention relates to a color video signal recording and reproducing system in which a color video signal is down-converted in frequency to a more recordable frequency range and then recorded on a record medium. In one form of the invention, the bandwidth of the video signal is split and each portion down-converted to a recordable frequency range for recording in separate tracks of the record medium.
2. Description Relative to the Prior Art
In general, color video signal recording and reproducing systems employing magnetic tape process a color video signal in a relatively complex manner for recording and then reverse the processing upon playback to form the original video signal. As is known, magnetic recording may be subject to the dropout of signal information, and such dropouts, which are usually caused by the playhead losing intimate contact with the tape, are frequency dependent. That is, it is easier to lose high frequency signal information than low frequency signal information during playback. To compensate for dropouts, and tape-flutter induced time base variations, special correction circuitry is generally included.
U.S. Pat. No. 2,921,976 relates to reproducing color television chrominance signals. In accordance with the patent, the chrominance signal is heterodyned with a constant frequency signal to produce a converted chrominance signal having a recordable frequency range. The heterodyning frequency can be "in the neighborhood of 3 mc or 4 mc; the exact frequency in this case is not particularly important". Upon playback, the frequency of the heterodyning signal employed to convert the recorded chrominance signal up to its original frequency range varies in response to the output of a discriminator. The discriminator compares the frequency of the color burst signal, as derived from the played-back video signal, with a fixed reference signal having a frequency of 3.58 MHz and produces an output signal indicative of the difference in frequency. This output signal is used to adjust the frequency of the heterodyning signal in such a manner as to compensate for time base variations. Systems in which information from the color burst signal is employed to achieve time base error correction are generally known as "burst" systems.
U.S. Pat. No. 3,723,638 discloses a color video signal recording and reproducing system in which the luminance and chrominance signals of a color video signal are separated. The luminance signal is used to frequency modulate a recordable carrier signal. The chrominance signal is frequency converted to a recordable frequency range. The frequency modulated luminance signal and frequency converted chrominance signal are superimposed and recorded. Upon playback, the luminance and chrominance signals are separated, the luminance signal demodulated, and the chrominance signal frequency converted to produce the originally recorded signal. The color burst signal from the played back chrominance signal is employed to compensate for time base errors introduced during the recording process.
U.S. Pat. No. 3,580,990 discloses a recording and reproducing system for color video signals which processes and records the luminance and chrominance signals similarly to the system disclosed in U.S. Pat. No. 3,723,638. Instead of using the color burst signal to correct for time base variations, however, a pilot signal is recorded along with the video information. Upon playback, phase variations in the pilot signal are employed to control time base errors in the reproduced chrominance signals. Time base error correction systems of this type are called "pilot" systems. Amplitude variations in the pilot signal are used to control the amplification given to the chrominance signal upon playback, thereby compensating the chrominance signal for tape-to-head dropouts.